Apparatus for fusing multifocal lenses



mm, 6, 1932. w. BAUSCH ET AL 1,889,769

APPARATUS FOR FUSING MULTIFOCAL LENSES Filed Aug. 9, 1929 INVENTORS ATTORNEY WILLIAM BAUSCH. JOHN R.POWELL.

. facturing fused multifocal lenses which are Patented Dec. 6, 1932 UNITED STATES PATENT OFFICE WILLIAM BA'USCH AND JOHNR. POWELL, O

F ROCHESTER, NEW YORK, ASSIGNORS TO BAUSCH & LOMB OPTICAL COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK nrranarus non resins monr'rr'ocar. unsns Application filed August 9, 1929. Serial No. 384,711. I

This invention relates to the art of manuformed segment by fusing a minor lens member or in a seat which has been formed on a major lens blank, the refractive indices of the major and minor members being different. More particularly this invention has reference to a method and apparatus for securing the two lens members in proper position during the fusing operation.

One of the objects of the present invention is to provide an improved method and means for holding the lens segment in proper position on the major blank during the fusing operation. Another object is to provide a device of the character described which will be simple and convenient and adapted for use on lenses of difierent thicknesses. A further object-is to provide a means which will rest solely on the major lens blank and which will hold the lens segment in proper position dun ing the fusing operation. Other objects and advantages reside in certain novel features of construction and combination of parts as will hereinafter be described and pointed out in the appended claims.

Referring to the drawing:

Fig. 1 is a side elevation illustrating the use of our device;

Fig. 2 is stop plan view of same.

Fig. 3 is a perspective view of our improved device.

Fig. 4 is a sectional view taken on line l-l of Fig. 2.

In manufacturing fused multiiocal lenses a seat or countersink is ground and polished on one surface of a major lens blank which is usually made of crown glass. The minor lens member or segment, having its under side suitably ground and polished, is generally made of flint glass which has a lower softening point than the crown glass. The segment is held in tilted position on the seat on the major lens blank, so that the segment contacts with the seat at one point. In this position the lens members are placed in a suitable furnace where, under the influence.

of heat, the flint segment gradually softens and drops into the seat on the major blank.

The fusion begins at the point of contact and properly hold the segment continues along progressively thereby goreventing the formation of air bubbles by entrained air.

Under one method of the prior art, a small I wire pin is placed on the major blank adjacent the edge of the countersink or seat. A cementitious substance is usually applied to the pin to keep it in place. The lens segment is then placed on the seat with one edge resting on the pin tliereby holding the segment in tilted relation to the major blank and in contact with it atone point. The lens members are then placed in a fusing furnace which may be provided with a travelling conveyorfor carrying the lens members through the furnace.

This method of using a wire pin is not entirely satisfactory because air bubbles are often formed around the pin and defective blanks are produced. Furthermore, after the lens segment has been placed on the major blank, subsequent handling and jarring caused by the travelling conveyor often cause a lateral movement or shifting oi the segment so that instead of being properly fused in the countersink, the segment only partly covers the countersink thereby producing a defective lens blank. lit will be readily noted, therefore, that it is of utmost importance to in place during the fusing operation. By means of our invention, however, we provide a simple and efficient device for properly holding the segment in position during the fusing operation.

One embodiment of our invention is illustrated in the drawing wherein 10 indicates the body member which may. preferably have a concave-convex shape whereby it is adapted to rest upon the convex surface of the major blank. The member 10 is provided with the integral. downwardly projecting lingers ll,

12 and 13 which are adapted to engage, loosely, the edge of the major blank. The member 10 is provided with anopening 1a which is adapted to receive the lens'segment. A. plurality of integral, upstanding projections 15, 16 and 17 may also be provided adjacent the edge of opening 14.

In using our improved device, a base 18, of refractory material, supports the major formed on its surface. Our device is then lens blank 19 having a countersink or seat 20 placed on top of the major blank 19 with the opening 14 arranged over the seat 20. The minor member or lens segment 21 is then placed within the opening 14 with one portion of the segment resting on the seat as indicated at 22 and with another portion of the segment resting on the shoulder portion 23 adjacent-the opening 14. The lens segment 21 is thereby held in tilted relation to the major blank 19 and the segment is also held against substantial lateral movement by means of projections 15, 16 and 17 These projections could be dispensed with as the sides of the opening 14 will serve to prevent substantial lateral movement of the segment.

From the foregoing it will be apparent that we are able to attain the objects of our invention and provide a simple and efiicient device for holding the segment in proper position during the fusing operation. The device can be manufactured of any suitable material which will withstand heat and will not adhere to the glass at fusing temperatures. The device can be formedor made by any suitable method. Additional material can be added to projection 13 to provide a thicker shoulder portion 23 on which the segment rests. Material could also be cut away from the body portion 10 to provide a ribbed structure.

Since the device rests solely on top of the major blank member, it can be used equally well on all major blanks irrespectiveof thickness, thereby eliminating the necessity of movable or adjustable parts. Likewise, the device can be used with segments of different thicknesses. When our device is used. the

lens segment is sopositioned that it entirely covers the seat or countersink on the major blank as the fused segment overhangs the periphery of the major blank. Hence, when the lens is finished by grinding and polishing a segment of maximum size can be obtained, thereby affording another important advantage. The device is simple in structure, etfieient in operation and canbe used repeatedly in fusing operations. Various modifications can obviously be made without departing from the spirit. of our invention as pointed out in the appended claims.

We claim:

1. For fusing multifocal lenses, a device formed to rest on the major lens blank, means on said device for holdinga lens segment in tilted position on the major lens blank, and means on said device for holding the segment against substantial lateral movement on the major lens blank.

2. A device for fusing bifocal lenses having means for holding a lens segment in tilted position upon a major lens blank, and means on said device for holding the lens segment against substantial lateral movement, said major lens blank.

3. For fusing multifocal lenses composed of a major lens blank and a segment fused on a seat formed in the surface of the major blank, a device comprising a member which is formed to rest on top of said major blank, means on said member for supporting the segment in tilted relation to said major blank and means on said member for holding the segment against substantial lateral movement.

4. A device for fusing bifocal lenses composed of a lens segment fused in a seat on a major lens blank, said device comprising a member having a concavo-convex shape whereby it is adapted to rest on top of the major blank, said member having an opening, means adjacent said opening for supporting the segment in. tilted position on said major blank and means adjacent said opening for holding the segment in adjusted position.

5. For fusing multifocal lenses composed of a major lens blank and aliens segment fused on a seat on a surface-of the major blank, a device comprising a member having a concavo-convex shape whereby it is adapted to rest on the major blank,.said member having a plurality of depending pro ections which are adapted to engage the edge of the major blank, said member having an opening for receiving the segment, a shoulder ad acent said opening for supporting the segment in tilted position ongthe major blank and means on said member) adjacent said openmg for preventing substantial lateral movement of the segment.

6. A device for fusing bifocal lenses comprising a member formed to rest on top of a major lens blank, said member having fingers adapted to engage the edge ofthe ma or blank, said member having an opening adapted to be positioned substantially over a countersink in the major lens blank and means adjacent to said opening for supporting a se ent in tilted relation to the countersink.

A device for fusing multifocal lenses comprising'a member adapted to rest on a major lens. blank, said member hav1ng an opening adapted to be positioned substantlally over a countersink in the lens blank, means on said member adjacent to said opening for holding a segment in tilted relation to the countersink and means on said member for holding the segment against substantial lateral movement.

WILLIAM BAUSCH. JOHN R. POWELL. 

